1. Field of the Invention
The present invention relates to an image forming device having a power saving mode, including a printing device, a facsimile device, a copying device and a digital copier, and relates to a method of controlling the image forming device.
2. Description of the Related Art
In recent years, there is a great demand for power saving of image forming devices from a viewpoint of environmental protection. In the case of the image forming device utilizing the electrophotographic process, the power consumption of its fixing unit is dominant. And the widely used method for attaining power saving of the image forming device is to suppress or stop the supply of electric power so that a temperature of the fixing unit in the standby mode is lower than that of the fixing unit in the active mode.
Recently, there is proposed an image forming device which stops the supply of electric power to not only the fixing unit but also the whole image forming device or most of the functional parts thereof during the power saving mode. For example, see Japanese Laid-Open Patent Application No. 11-126000.
According to the above-mentioned image forming device, it is possible to reduce the power consumption in the standby mode to less than several watts (W) by setting the image forming device in the power saving mode, and it is possible to increase the power-saving effect.
However, even when a return factor which is detected by the system control unit during the power saving mode does not require initialization processing of the electrophotographic process (for example, when a device management command, such as an inquiry of paper size of a main part cassette, is received from an external device connected to the image forming device via a network), the engine control unit starts performing the initialization of the electrophotographic process as soon as it is started, without awaiting the completion of starting of the system control unit. For this reason, in the case of the above-mentioned image forming device, there are such problems that the unnecessary power consumption may arise or noises may occur accompanied with the initialization processing.